Submitted to: Asian Symposium on Plant Lipids
Publication Type: Abstract Only
Publication Acceptance Date: 9/27/2013
Publication Date: N/A
Technical Abstract: P Lesquerella [Physaria fendleri (A. Gray)], formerly Lesquerella fendleri, (Brassicaceae), being developed as a new industrial oilseed crop in the southwestern region of the United States, is valued for its unusual hydroxy fatty acid (HFA) in seed. The majority of HFA in lesquerella is lesquerolic acid (20:1OH) comprising 55-60% of total seed fatty acids. The conventional source of HFA is from castor (Ricinus communis); 90% of castor oil is ricinoleic acid (18:1OH). Ricinoleic acid and its derivatives are used as raw materials for numerous industrial products, such as lubricants, plasticizers and surfactants. The production of castor oil, however, is hampered by the presence of the toxin ricin and hyper-allergic 2S albumins in its seed. Lesquerella, on the other hand, does not have such biological toxic compounds, thus its oil represents a safe source of HFA. To understand HFA synthesis and regulation in lesquerella, we investigated morphological and physiological changes, as well as temporal details of fatty acid composition and gene expression during seed development. We found that the synthesis of 20:1OH is regulated largely by gene transcription of LfKCS3. It is known that most of the HFAs in L. fendleri are located only at sn-1 and sn-3 positions of triacylglycerol (TAG). This suggests that it may be possible to enhance HFA accumulation in lesquerella seeds by manipulating a lysophosphatidic acid acyltransferase (LPAT) that favors incorporation of hydroxy acyl groups at the sn-2 position. A castor gene, RcLPAT2, has been transformed into lesquerella. Analysis of fifteen transgenic lines (T1 seeds) carrying RcLPAT2 showed that all lines increased in 18:1-OH content in the seeds compared to the wild-type, indicating RcLPAT2 preferentially puts 18:1-OH into TAG in lesquerella. The results advance our understanding of regulatory mechanisms underlying synthesis and accumulation of HFAs, which are useful to the development of an 18:1OH-producing lesquerella crop through genetic engineering.